The invention relates to a method for producing a piston ring having an axial height <2 mm.
In the general prior art, the running surface of, for example, electroplated, profile-ground spiral expander rings with and without a profile, can be machined up to a ring height of 2 mm. Usually both rail flanks are machined symmetrically and inclusive of the outer groove. (One may also refer to the rails as “ridges,” for example.)
DE 100 02 282 C1 discloses a method for producing an oil scraper piston ring as well as an oil scraper piston ring produced by the method. The method for producing the oil scraper piston ring, which includes at least one tapered running rail provided with a wear-resistant coating, is carried out by, prior to the application of the wear-resistant coating, producing a profile on each tapered running rail on the surface thereof which comprises the outer circumferential surface of the ring and the wear-resistant coated surface of which will be a running surface of the running rail, the profile including a radial elevation formed by a portion of the circumferential surface of the rail projecting radially outward from another circumferential portion thereof, and then providing the profile with at least the wear-resistant coating, and carrying out a predefinable removal of material from the coating at least in the region of the radial elevation in order to produce a running surface profile that is substantially uniform around the ring circumference, and then profile-grinding the running rail flanks so that a defined cylindrical remaining surface is produced in at the radial elevation.
Today, this technique is used on piston rings, in particular oil scraper piston rings, having a ring height of up to 2 mm. The unceasing development of internal combustion engines now demands a further adaptation of the piston ring height in ranges up to 1.5 mm or less. According to the current state of the art, such rings can no longer be profile-ground on the running surface because the axially smaller dimensioning of the running surface shape cannot be achieved by the available grinding disk technology.